Automatic non-bobbin lower thread-supplying apparatus for industrial sewing machine

ABSTRACT

An automatic non-bobbin lower thread-supplying apparatus for industrial sewing machine is introduced to resolve a limited lower thread-supply problem on a conventional bobbin of hook, which the problem will lead to frequent work on replacing the bobbin during a sewing operation and obviously is both time-consuming and quality-reducing. In the present invention, the conventional bobbin is abandoned by providing a throughout center aperture to a lower shaft that drives the hook. The center aperture forms a passage for the lower thread from a center hole of a transmission gear at one end of the lower shaft to the center of hook at another end thereof. By providing the center aperture of the lower shaft, the lower thread can be introduced from outsides of the sewing machine and directly supplied to the hook without frequently replacing the bobbin during the sewing operation.

BACKGROUND OF THE INVENTION

[0001] (1) Field of the Invention

[0002] The invention relates to an automatic non-bobbin lower thread-supplying apparatus for industrial sewing machine, and more particularly to an apparatus that can provide the lower thread from outsides of the sewing machine and keep feeding the lower thread without frequently replacing the bobbin.

[0003] (2) Description of the Prior Art

[0004] It is well known in the art that a sewing machine utilizes a sewing method different from a hand-made sewing operation. The hand-made operation applies a sewing needle introducing a single sewing thread to pierce reciprocally upon a work piece. On the other hand, the conventional sewing machine utilizes a sewing needle and two sewing threads. In the machine sewing, one sewing thread (say, lower thread) )is placed under the work piece and the other (say, upper thread) is placed upon the work piece. The sewing needle is used to pull the upper sewing thread downward to penetrate the work piece, further to net the upper thread with the lower thread through a hook under the work piece, and to pull the upper sewing upward back to an upper position over the work piece. Then, the work piece is fed by a predetermined displacement for another sewing cycle. By repeating aforesaid sewing cycles, the sewing machine can sew two work pieces together. It is noted that the upper thread is introduced to the sewing needle directly from a reel outside the sewing machine and the lower thread is provided from a bobbin mounted inside a center of the hook. For a clear understanding about the aforesaid sewing method, a detail description upon the conventional method of introducing the lower thread as well as accompanying disadvantages thereof is present as follows.

[0005] Referring to FIG.1 and FIG.2, exploded perspective views upon a conventional lower thread-supplying apparatus and a sewing needle are present. As shown, the sewing needle 1 and the hook 2 are displaced upon and below a needle plate 3, respectively. The work piece (not shown in figures) is moved back and forth upon the needle plate 3. The upper thread 11 outside the sewing machine is introduced to the sewing needle 1 through a center hole thereof, in which the sewing needle 1 is driven up and down by the machine. While in the sewing operation, the lower thread 11 is pulled to go through a thread aperture 31 of the work piece along with the sewing needle 1, and is netted with the lower thread 51 at the hook 2. Then, the lower thread 11 is pulled back by the sewing needle 1 to the original upper position above the work piece. If a second sewing is required, the work piece will make a predetermined displacement and proceed the following sewing. In the conventional sewing machine, the hook 2 is installed to a lower shaft 4 which is driven by a spindle (not shown in figures) through a transmission gear 41. In a sewing operation, rotation of the lower shaft 4 is corresponding to the linear motion of the sewing needle 1 which is also driven by the spindle. Upon such an arrangement and by providing the configuration of the hook 2, the lower thread 51 and the upper thread 11 can be netted.

[0006] In FIG. 2, the hook 2 of FIG. 1 is further exploded. As shown, the hook 2 includes a bobbin 22 and a bobbin case 21. While in use, the lower thread 51 is wound around the bobbin 22. It is interesting to aware that the lower thread 51 is named due to its location under the work piece. A bobbin filled with thread 5 is then mounted into the hook 2, and covered by a bobbin case 21 as shown in FIG. 1. The combination of the hook 2 can then be used in a sewing operation. Nevertheless, a major disadvantage of the aforesaid conventional sewing machine is limited capacity of providing lower thread 51. As described above, the lower thread 51 is wound on the bobbin 22 and the bobbin 22 is further located to a limited room inside the hook 2. Therefore, it can be foreseen that the conventional lower thread-supplying apparatus can only supply a limited length of the lower thread 11. For example, the bobbin 22 with a diameter of 2 to 3 cm can provide 20 to 30 yards of a normal lower thread 11 with 20 lines. That is to say, the respective work piece can only be continuously sewed for a distance of 20 to 30 yards. After that, a shutdown of the sewing machine to proceed a replacement of a bobbin filled with thread 5 is required. It is obvious that such a replacement work is labor-consuming and a substantial length of the lower thread 51 (odd piece) will be wasted while replacing the bobbin 22. It is equivocal to manage the odd piece 51. Some operators will cut the odd piece 51 off, but it is quite possible to introduce an escaping thread in the sewing. On the other hand, some operators will leave the odd piece 51 there, but lead to an ugly appearance which is usually seen on a new clothes. Contrary to the lower thread 51, the upper thread 11 is provided by a reel located outside the sewing machine. Generally, the industrial sewing machine usually uses a two-pound reel. In the case that a thread of 20 lines is used as the upper thread 11, the 2-pound reel can provide a thread of 16,800 yards long. Unlike the application of the lower thread 51, the upper thread 11 can be continuously used for months without any replacement.

SUMMARY OF THE INVENTION

[0007] Accordingly, it is a primary object of the present invention to provide an automatic non-bobbin lower thread-supplying apparatus for industrial sewing machine which can resolve the aforesaid limited-length problem of the conventional lower thread-supplying apparatus.

[0008] In the present invention, the automatic non-bobbin lower thread-supplying apparatus is simply structured, in which the conventional bobbin is abandoned and the lower shaft is bored to provide an interior concentric passage that can allow the lower thread to pass the central aperture of lower shaft from the outsides and to leave the shaft from a right side of the transmission gear. The lower thread provided from the central aperture of lower shaft can then be introduced to the center of the hook for replacing the conventional lower thread that is used to wind around a bobbin inside the hook. By providing the present invention, the lower thread can be supplied from a reel located outside the sewing machine so that frequently replacing the bobbin in the conventional sewing machine can be avoided.

[0009] All these objects are achieved by the automatic non-bobbin lower thread-supplying apparatus for industrial sewing machine described below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention will now be specified with reference to its preferred embodiment illustrated in the drawings, in which

[0011]FIG. 1 is an exploded perspective view showing the relationship between a lower thread-supplying apparatus and a sewing needle for a conventional sewing machine;

[0012]FIG. 2 is a further exploded perspective view of the lower thread-supplying apparatus of FIG. 1;

[0013]FIG. 3 is an exploded perspective view of a preferred lower thread-supplying apparatus in accordance with the present invention; and

[0014]FIG. 4 is a schematic view of a preferred lead thread hook in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0015] The invention disclosed herein is directed to an automatic non-bobbin lower thread-supplying apparatus for industrial sewing machine. In the following description, numerous details are set forth in order to provide a thorough understanding of the present invention. It will be appreciated by one skilled in the art that variations of these specific details are possible while still achieving the results of the present invention. In other instance, well-known components are not described in detail in order not to unnecessarily obscure the present invention.

[0016] Referring now to FIG. 3, a preferred lower thread-supplying apparatus in accordance with the present invention is illustrated. As shown, the lower shaft 4 is bored to provide a throughout center aperture 42 for allowing the lower thread to be introduced through a center hole of the transmission gear 41 into a center of the hook 2. Thereby, the conventional bobbin 22 for winding the lower thread is substituted. To prevent the introducing of the lower thread from interfering with other components of the sewing machine, a thread conduit 6 is provided at an appropriate location adjacent to the transmission gear 41, for leading the lower thread from an outside reel (not shown in figures) to the center hole of transmission gear 41. Obviously, the present invention keeps the bobbin case 21 but get rid of the bobbin 22, so that the interior of the hook 2 can be still isolated from the outside particles or objects.

[0017] Referring now to FIG. 4, a lead thread hook 7 for leading the lower thread is shown. The lead thread hook 7 can be made of flexible steel wire and include a ring 71 at one end (front end) thereof and a thread aperture 72 at another end (rear end) thereof. Because the lower shaft 4 of industrial sewing machine has a substantial length, it is not an easy job to lead the lower thread all the way directly from the transmission gear 41 to the center of the hook 2. Yet, by providing the lead thread hook 7, the difficulty in leading the lower thread can be relieved. While introducing the lower thread, the lead thread hook 7 is placed to penetrate the center aperture 42 of the lower shaft 4 from the center of the hook 2 to the center of the transmission gear 41. Then, one end of the lower thread can be anchored inside the thread aperture 72. After the lead thread hook 7 is pulled out the lower shaft 4 by the ring 71 at the hook 2, the lower thread along with the thread aperture 72 can be easily pulled to the center of the hook 2.

[0018] By providing the present invention, though the structure thereof is simple, yet a substantial amount of laboring can be saved, the production can be increased, and the notorious problem of odd piece can be resolved.

[0019] While the present invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be without departing from the spirit and scope of the present invention. 

I claim:
 1. An automatic non-bobbin lower thread-supplying apparatus for industrial sewing machine, characterized in that a throughout center aperture for allowing a thread to pass therebythrough is provided to a lower shaft of the sewing machine, in which the center aperture connects a center of a hook of the sewing machine with a center hole of a transmission gear of the sewing machine. 